Type Element type "class-loader" must be declared. glassfish-web.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE glassfish-web-app PUBLIC 
"-//GlassFish.org//DTD GlassFish Application Server 
3.1 Servlet 3.0//EN"
" http://glassfish.org/dtds/glassfish-web-app_3_0-1.dtd">


<glassfish-web-app error-url="">
      <class-loader delegate="true"/>
</glassfish-web-app>

Element type "class-loader" must be declared. glassfish-web.xml /julian/src/main/webapp/WEB- The error message is unclear. If you know what it means please share